I was wondering if flower stalks forms callus in the dark. I have trouble keeping sterile flower stalks green and fresh. Due to the hot weather and keeping them on culture in my growth cabinet (which also produce some heat of the lamps), they decompose faster. I have some stalks in culture in a locker at work, where the temperature is more constant (20ºC). But there is no light, so does callus form in the dark or should I introduce them into the light?